Robot arm



FIG. 1 is a front perspective view of a robot arm showing my new design;

FIG. 2 is a rear perspective view thereof, showing the side opposite that shown in FIG. 1;

FIG. 3 is a side elevational view taken from the left of FIG. 1;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a side elevational view taken from the right of FIG. 1;

FIG. 6 is a rear elevational view thereof;

FIG. 7 is a top plan view thereof, the bottom being unornamented. 

The ornamental design for a robot arm, as shown and described. 